Integrated circuits (ICs) require reliable interconnections for proper operation. Illustrative integrated circuits include digital ICs, analog ICs, and mixed signal ICs.
Regulators, or converters, including a switch for transferring energy from an input, such as an AC or DC voltage or current source, to a regulated output are well known. In some regulators, sometimes referred to as switching regulators, the switch turns on and off to regulate the output. Common switching regulator configurations include Buck, Boost, Buck-Boost, flyback, SEPIC, Cúk, half bridge, and full bridge to name a few. Such switching regulators include an inductor to convert the switched current pulses into a continuous load current. In other regulators, sometimes referred to as linear regulators, the switch operates in its active, or saturation region.
Regulators often require the regulated output to be coupled to a switch control circuit in a feedback relationship (i.e., to a feedback input of the control circuit) for use in controlling the switch(es) that transfer energy from the input to the output. If this feedback connection from the regulated output to the switch control circuit were to become disconnected (i.e., referred to herein as an “open pin condition”), then the integrated circuit may increase the output to the load, providing a damaging voltage or current to the load. One technique for detecting such an open pin condition is to introduce a relatively small current into the feedback input of the regulator which, in the presence of an open pin condition, would increase the feedback voltage to a level that would cause the control loop to drive the output voltage low and possibly trip an overvoltage protection circuit.